Symptoms

Blood in Urine: Causes and Tests

Seeing blood in the urine is frightening, and it should never be ignored, even if it happens only once, stops by itself or does not hurt. Most causes are not cancer, but this symptom is the commonest first sign of bladder and kidney cancer, so it needs to be checked properly.

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Written for patients and reviewed by Dr. Anshuman Singh, Uro-Oncologist, on 7 October 2026.

Two kinds

Visible and microscopic blood

Visible blood (gross haematuria)
The urine looks pink, red, brown or tea-coloured, sometimes with clots. It can come and go.
Microscopic blood
The urine looks normal, but a urine test shows red blood cells. Often found on a routine check, it also needs evaluation, especially after about 40 years of age or in smokers.

Possible causes

Why there may be blood in the urine

Urine infection
Usually with burning, urgency and frequent urination.
Stones
In the kidney, ureter or bladder, often with colicky pain in the side.
Enlarged prostate
In older men, enlarged prostate veins can bleed.
Kidney conditions and injury
Some kidney diseases, or a blow to the side or back.
Medicines
Blood thinners can bring out bleeding, but they do not explain it away. The urinary tract still needs to be checked.
Cancer
Bladder cancer, kidney cancer, upper tract (ureter) cancer and, less often, prostate cancer. Bleeding from a cancer is often painless and may stop for days or weeks, then return.

Why it matters

Why even one episode needs a check

  • Cancer can cause blood in the urine that stops by itself, and a pause in bleeding does not mean the cause has gone.
  • Painless blood in the urine is more suspicious than blood with burning or pain, though pain does not rule out cancer.
  • Risk is higher with smoking, age over 40, past exposure to dyes or chemicals, and some earlier pelvic radiotherapy or medicines.
  • Finding a bladder or kidney cancer early gives more treatment options, often including keeping the bladder or kidney.

The tests

What evaluation usually involves

Urine tests
A urine test and culture to look for infection and confirm blood. Urine may also be checked for cancer cells.
Blood tests
Kidney function and blood counts, and PSA in men when appropriate.
Ultrasound
A quick, painless scan of the kidneys and bladder.
CT urogram
A CT scan with contrast that shows the kidneys, ureters and bladder in detail.
Cystoscopy
A thin camera passed through the urine passage to look inside the bladder. It is usually done in the clinic with local anaesthetic, and it is the test that finds most bladder tumours.

What next

If a tumour is found

A bladder tumour is usually removed through the urine passage with no cut (TURBT), and the sample shows how deep it goes and how aggressive it is. This decides whether further treatment such as BCG is needed or, less often, whether the bladder must be removed.

A kidney or ureter tumour is staged with scans, and treatment may range from a partial operation that keeps the kidney to removal of the kidney and ureter. Each is explained, with the options for your stage, in the Cancer Pathway guides.

Prepare

What to bring to the consultation

  • All urine, blood, ultrasound, CT and cystoscopy reports, with dates.
  • A note of when the bleeding happened, how long it lasted, and whether there was pain, clots or fever.
  • A list of your medicines, especially blood thinners and aspirin.
  • Your smoking history and any work exposure to dyes or chemicals.

When to get help quickly

  • You are passing clots or cannot pass urine.
  • Heavy bleeding that does not settle, or dizziness.
  • Fever, shivering or severe pain in the side or back.

Read next

Related guides

A free patient tool

Even microscopic blood needs a check. This shows which tests are usually advised.

Blood in the urine: what evaluation is needed?

Common questions

Questions patients ask

I saw blood in my urine once and it stopped. Do I still need tests?

Yes. Bleeding from a bladder or kidney tumour can stop for weeks. A single episode should still be evaluated.

Does painless blood in the urine mean cancer?

Not always, but it is a pattern that needs a careful check, because bladder and kidney cancers often cause painless bleeding.

Could it be only a urine infection?

It can be, especially with burning and frequency. If the blood returns after treatment, or you are over 40 or smoke, further tests are advised.

I take blood thinners. Is that the cause?

Blood thinners can make existing problems bleed, but they do not cause blood in the urine on their own, so the cause should still be looked for.

Is cystoscopy painful?

It causes some discomfort, usually mild. It is done with local anaesthetic gel and takes a few minutes. Some burning for a day afterwards is common.

Can blood in the urine in a young person be cancer?

It is less likely at a young age, but it still needs an evaluation, because the causes include stones, infection and kidney conditions that need treatment.

Talk it through with Dr. Anshuman Singh

This page is general information and does not replace a medical opinion. An unhurried one-to-one discussion with Dr. Anshuman Singh, with your family welcome, so that you understand every option before you decide. About Dr. Singh

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